1. Field of the Invention
The invention relates to a method and a device for opto-electrical acquisition of shapes.
2. Brief Description of the Prior Art
A number of techniques for opto-electrical acquisition of shapes are known in the art:
stereovision consists of deducing the relief of a surface by comparing images of the surface captured at two different angles at least; this method requires very large computing means, is limited to parts of the surface that are visible from both angles at the same time, and the location of edges is imprecise, PA1 observation of a surface by a video camera whose focussing is varied, which associates a distance (the focussing distance) with each clear area of an image of the surface; this system requires very large computing means, the measurement times are long and the spatial resolution is not very good, PA1 measuring the time taken by a light pulse to travel the distance between an emitter and the surface and between the surface and a receiver, or measuring the phase shift between modulated illumination projected onto the surface and the observed light backscattered by the surface; these means acquire points and must be associated with scanning means, which limits the acquisition speed, PA1 triangulation determines the length of the two sides of a triangle when two angles of the triangle and the length of the third side are known, and one application of triangulation consists of projecting a structured light flux onto the surface, using a video camera to observe the deformations of the flux by the surface and deducing therefrom, by triangulation, the distances of points on the surface relative to a reference plane; this technique suffers the limitations of triangulation (it requires the largest possible distance between the illumination means and the video camera and different illumination and observation directions), with the result that complex surface areas cannot be illuminated and observed simultaneously. PA1 the illumination means generate a plurality of light beams having different wavelengths and converging on an axial illumination direction at different points distributed along that direction, PA1 the means for analyzing the light reflected or backscattered by said surface include spectral analysis means, and PA1 the information processing means determine the distances of points of said surface from the spectral composition of the light analyzed.